The photo Col. Aldrin refers to was snapped on an extra-vehicular activity during the Gemini 12 mission in November 1966. A professor at Northwestern University had arranged for the astronauts to take ultraviolet photos of the stars, using a camera mounted to the outside of the spacecraft. The experimental photos would be taken during darkness, but when the shuttle passed into daylight, Col. Aldrin couldn't help snapping a picture of himself with the earth behind him.